1). Field of the Invention
Embodiments of this invention relate generally to semiconductor manufacturing. More specifically, embodiments of this invention relate to a method of plug fill for high aspect ratio plugs.
2). Discussion of Related Art
Existing plug fill techniques suggest conformal deposition of metals or top to bottom fill by sputtering. For example, a via is formed within a dielectric material formed on a semiconductor containing layer. Conductive material is deposited within the via down the sidewalls to the bottom of the via. The conductive material fills the via inward from the sidewalls and up from the bottom of the via. This results in a seam being formed when the via is filled. Also, prior art techniques typically use an adhesive barrier on the sidewalls.
In another example technique, a via is formed within a dielectric material formed on a semiconductor containing layer. Conductive material is deposited within the via by sputtering. When the conductive material is sputtered into the via, it collects on the sidewalls and on the bottom of the via. The conductive material fills the via inward from the sidewalls and up from the bottom of the via. This results in a seam being formed when the via is filled.
The prior art methods have a strong dependence on plug aspect ratio, so that at a high aspect ratio, the quality of the plug is significantly reduced. In these methods, the plug fill accumulates on the side walls and grows inward from the side walls. One of the known downsides is the creation of a seam. Further interaction with polishing can cause the seam to expose and further result in trapping polishing by-products. With node size reduction, the problem with plug aspect ratio becomes more crucial. Thus, plug fill with high aspect ratio for 45 nm node and beyond technologies, for example, requires completely new generation of hardware.
What is needed is a method of plug fill which avoids the problems discussed above regardless of the plug aspect ratio.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.